EU study demonstrates grouping and read-across for nanomaterials

European Commission scientists have demonstrated the use of Echa’s recommendations on grouping and read-across for nanomaterials through a study of multi-walled carbon nanotubes.

The group from the Commission’s Joint Research Centre (JRC) followed guidance document Recommendations for Nanomaterials Applicable to the Guidance on QSARs and Grouping.

In particular, they applied grouping and read-across methods to 19 types of nanotubes to fill data gaps on genotoxicity. They also applied chemoinformatics to complement these methods.

The study was led by the JRC’s Karin Aschberger and published in Computational Toxicology.

The aim of the study was not hazard assessment, but nevertheless the data chosen for illustrative purposes suggested that the nanotubes used in the study were not genotoxic, the scientists said in their paper.

In particular, the study found no major differences between the nanotubes that could be attributed to differences in physicochemical properties such as length, diameter or rigidity. However, these properties might have an impact on other hazard endpoints, such as carcinogenicity, the scientists added.

Echa’s Read-Across Assessment Framework (RAAF) was used to characterise the uncertainties in the results.

In their paper, the scientists recommended some changes to the workflow in the guidance to enhance usability and simplify reporting.

Environmental release

A paper published in Nanotoxicology on 7 February outlined how data on environmental release and exposure for nano-forms might be incorporated into grouping and read-across techniques.

Henning Wigger and Bernard Nowack from the Swiss Federal Laboratories for Materials Science and Technology (Empa) said that the incorporation of this data is required for "complete" risk assessments.

"Our results suggest that grouping and read-across concepts should include both a nano-form release potential for estimating the environmental exposure and separately consider the nano-forms in environmental risk assessments."

They demonstrated their approach with data on titanium dioxide nanoparticles, carbon nanotubes and aluminium oxide nanoparticles. They found variation in environmental concentration for nano-forms of the same nanomaterial, such as single- and multi-walled carbon nanotubes.